Missile fuses

ABSTRACT

A fuse for a ballistic missile comprising a hammer and a firing chain so arranged that when the missile strikes its objective the hammer penetrates the firing chain and causes the missile to explode. The firing chain includes two detonators carried in a rotor which has a safety position in which the detonators are out of alignment with the firing hammer, the detonators being brought into active position with a delay period after firing of the missile due to an imbalance in the rotor so that rotation of the missile after firing causes the detonators to be aligned with the hammer. In consequence when the missile strikes an objective after a predetermined time from the initiation of its flight the hammer penetrates the detonators and causes the missile to explode.

United States Bares atent Feb. 13,1973

l54l MISSILE FUSES [75] Inventor: Roger Bares, Roques S/ Garonne,

France [73] Assignee: Societe E. Lacroix 221 Filed: July 29, 1970 [21]Appl. No.: 59,126

[30] Foreign Application Priority Data Aug. 26, 1969 France .6929160[52] US. Cl ..102/80, 102/78 [51 1 Int. Cl. ..F42c 15/26 [58] Field ofSearch ....l02/76, 79, 80, 70

[56] References Cited UNITED STATES PATENTS 3,500,748 3/1970 Hager etal. 102/79 2,977,883 4/1961 Czajkowski ..l02/79 FOREIGN PATENTS ORAPPLICATIONS 17,795 1905 Great Britain ..102'/8O PrimaryExaminer--Samuel W. Engle Attorney-Andrus, Sceales, Starke & Sawall [57]ABSTRACT A fuse for a ballistic missile comprising a hammer and a firingchain so arranged that when the missile strikes its objective the hammerpenetrates the firing chain and causes the missile to explode. Thefiring chain includes two detonators carried in a rotor which has asafety position in which the detonators are out of alignment with thefiring hammer, the detonators being brought into active position with adelay period after firing of the missile due to an imbalance in therotor so that rotation of the missile after firing causes the detonatorsto be aligned with the hammer. In con sequence when the missile strikesan objective after a predetermined time from the initiation of itsflight the hammer penetrates the detonators and causes the missile toexplode.

E we 3 \b- F 1 m '2 l6 to 33m MISSILE FUSES The present invention isconcerned with a fuse for missiles, projectiles or shells.

It is known that a fuse for a missile is an arrangement associated withthe missile and adapted to make it explode when the latter strikes itsobjective.

Such a fuse generally comprises a hammer and a firing or pyrotechnicchain disposed in such a manner that the hammer, under the effect of theimpact of the projectile on its objective, penetrates into a detonatoror percussion cap and initiates the firing chain which causes the shellto explode.

For reasons of safety, the fuse must be inert or the chain interrupted,on the one hand, when the shell is in storage and, on the other hand,for an initial part of the trajectory of the shell when the shell isfired. Further, the fuse must be armed a certain determined distanceafter the instant of firing.

To attain these objectives, the fuse, according to the invention,comprises a rotatably mounted member, or rotor, carrying the activefiring or pyrotechnic chain and able to take up two positions, namely afirst position called safety in which the rotor is locked in such amanner that the firing chain is interrupted and a second position calledalignment in which the firing chain is continuous, the passage from the"safety" position to the alignment position being effected under theeffect of the rotation of the projectile due to a want of balance of orunbalance in, the rotor, the hammer also being able to take up twopositions, namely a locking position in which it secures the rotor inthe safety position and an armed position in which the rotor is free totake up the alignment" position, a delaying arrangement being providedwhereby the hammer passes from the locking position to the armedposition with a predetermined delay after firing of the missile.

An embodiment of the present invention will now be described, by way ofexample, with reference to the accompanying drawings in which:

FIG. 1 is an axial section of a fuse according to the invention, in theinert position;

FIGS. 2 and 3 are sections of the fuse of FIG. 1 respectively on thelines II-II and III-III;

FIG. 4 is a similar view to FIG. 1 with the fuse armed; and

FIG. 5 is a similar view of the fuse at the instant of impact.

In FIG. 1, reference 1 designates the point or leading end 1 of thefuse, which is appreciably of parabolic form and open at the bottom. Thefuse comprises a hammer 2 and a firing or pyrotechnic chain constitutedby a primary detonator 3, a second detonator 4 and a booster 5. Theprimary and secondary detonators 3 and 4 constitute the active firing orpyrotechnic chain.

The hammer 2 is constituted by a tail 6 and a piston 7 slidably mountedin the chamber 8 of cylinder or housing 8a filled with balls 9, thepiston 7 pressing on the balls under the action of aspring 10.

The part of the firing chain constituted by the two detonators 3 and 4is mounted in a rotatable member, or rotor 11. The rotor 11 is mountedfor rotation about an axis perpendicular to the plane of the Figure (andthus also to the axis of the fuse) and rests in bearings provided forthis purpose in a member 12 supported on the body 13 of the fuse and isheld thereon by a member 14. The member 12 is constituted by acylindrical receptacle comprising a base 12a and a cylindrical wall 12bin which are cut two borings 23 and 24 serving as the bearings for axles25 and 26 of the rotor 11, and two openings 27 and 28 to permit locationand pivoting of the rotor 11. The holding member 14 also has the formofa body of revolution. It has two projecting parts 29 and 30 which reston the axles 25 and 26 of the rotor to maintain the latter in place. Themember 14 has a central boring 31 for receiving the tail 6 of the hammerand serving thus to support the hammer.

The spring 10 rests also on a shoulder of this holding member 14.

The booster 5 is mounted in the body 13. The rotor is formed so as tohave a want of balance or unbalance, that is to say, its center ofgravity does not coincide with the axis of rotation, and it thus has adefined sense of rotation. This want of balance or unbalance is obtainedfor example due to a displacement of the axis of the detonators relativeto the axis of the fuse (FIG. 1) obtained by machining a face of therotor. It must be noted that the fuse in its assembly has no want ofbalance or unbalance which is very important to limit the movement ofprecession of the shell.

A boring 15, cut in the rotor, serves to receive the tail 6 of thehammer to lock the rotor in the safety position shown (FIG. 1) in whichthe firing chain is interrupted. It is to be noted that in the case ofaccidental initiation of the detonators, the action of their explosionis directed towards the exterior and in no instance towards the booster5.

The rotor has a cut-out 16 serving to lock the rotor on a pin in thealignment position as will be seen later.

Around the cylinder 8a is slidably mounted a ring 17 held by pins 18.The hammer is maintained in axial alignment by the support member 14screwed on the cylinder 8.

The operation of the fuse is as follows:

At the instant of the firing or shot, the ring 17, by inertia, shearsthe pins 18 under the effect of acceleration and slides till a resilientring 19 carried by the ring 17 comes to wedge behind a shoulder 20 ofthe fuse body. The sliding of the ring 17 towards the fuse bottomuncovers a hole 32 cut in the cylinder 8a permitting the outflow of theballs 9 from chamber 8 into the space between the pointed casing 1 andcylinder 8a. The ejection of the balls is effected under the action ofthe hammer 2 moving into the chamber 8 thanks to the spring 10 so asfinally to take up the armed position in which the tail of the hammerhas left the boring 15. This results in the rotor 15 rotating in thepredetermined direction under the action of centrifugal force resultingfrom rotation of the missile. The rotor turns through due to its want ofbalance or unbalance. The rotation is limited by a pin 33 abutting theend of the peripheral cut-out 16 in the rotor 11 so that the firingchain aligns automatically with the hammer. This abutment permits aperfect alignment whatever may be the speed of rotation of the missile.

At impact of the missile on its objective, the nose of the fuse iscrushed which forces the tail of the hammer into the primary detonator 3which detonates so actuating the secondary detonator 4 and the booster5.

The booster 5 finally makes the shell explode.

The angle of impact and the nature of the objective have greatimportance on the firing or non-firing of the fuse so that thesensitivity of the fuse is variable and difficult to determine inadvance.

This problem is resolved by the fact that the wall of the cylinder 8aenclosing the balls and the hammer is constituted of two cylindricalparts of different diameters connected'by a shoulder 21.

At impact, this shoulder is crushed, the front part of the cylinder 8apenetrating into the rear part of a greater diameter so that the hammerplays its role in penetrating into the primary detonator (FIG.

As the necessary crushing force can be easily calculated knowing thethickness of the shoulder 21 and the desired sensitivity, it issufficient to select a thickness suitable for the desired object.Further, the pointed end 1 has a line of rupture 22 so that on impactthe upper part of the fuse body is forced into the lower part; thisresults in a greater regularity in the sensitivity of the fuse (FIG. 5).

The delaying arrangement is constituted by the system of balls andpermits the introduction of a predetermined delay in a precise manner inthe arming of the fuse. In one embodiment, this delay is controlled insuch a manner that it corresponds to a distance of about 60m. Thus, oneis sure that the shell will not explode if it meets an obstacle withinthis distance.

The delay may be a little greater but it is made to match a givendistance, for example 100m from the departure of the missile, before thefuse is armed with certainty.

What is claimed is:

1. A fuse for a missile, comprising a casing having a booster at therear end of the casing for exploding of the missile, a rotor adjacentthe rear end of the casing carrying detonator means and adapted to berotated from a safety position to a firing position, a movable hammeradapted at the rear end thereof to engage the rotor to hold the rotor inlocked safety position, and actuating means for moving the hammer out ofengagement with the rotor to permit rotation of the rotor from thelocked safety position to an armed position whereby the detonator meansis placed in line with the hammer when the fuse is actuated for firing,the said fuse having a safety arrangement for locking the hammer in therest position and for allowing the hammer to move from the rest to thearmed position only after a predetermined time delay after firing of themissile, characterized by a housing in said casing having a chambertherein, a piston on the forward end of said hammer adapted to beslidably received in the chamber of said housing, a plurality of ballsconfined in said housing by the piston on said hammer with the ballsnormally holding the hammer in rest position, an exit passage in thewall of the housing from said chamber, and an inertia operated memberslidably mounted on said housing and closing said exit passage when thefuse is in rest position and slidable to a position to open said exitpassage when the missile is fired to permit flow of the balls throughthe exit passage over a predetermined delayed period of time so that thehammer is free to move forward out of engagement with the rotor and therotor is then free to rotate under centrifugal force to position thedetonator in position to be detonated by the hammer when the fusestrikes an obiect.

A fuse according to claim 1, wherein the inertia operated member is aring assembled around said cylinder, pin means securing the inertiaoperated member in the position to close the aperture and being shearedupon firing of the missile by the inertia operated member as the latterby inertia slides on said cylinder and opens said aperture for releaseof the balls from the cylinder.

3. A fuse according to claim 1, wherein the rotor has a centralelongated hole to receive the inner end of the hammer to hold the rotorin non-firing position.

4. A fuse according to claim 1 wherein said housing is an axiallyextending cylinder with one portion of the cylinder having a greaterdiameter than a second portion and an annular shoulder therebetween,said shoulder adapted to be crushed on impact of the fuse.

5. A fuse according to claim 1, and bearing means mounted within thecasing for supporting the rotor, said bearing means comprising a hollowcylindrical member having two opposed openings extending in onedirection to receive the rotor in the openings and support the rotor forrotation on the cylindrical member, and two other openings in thecylindrical member in a direction at right angles to the first statedopenings permitting rotation of the rotor therein.

1. A fuse for a missile, comprising a casing having a booster at therear end of the casing for exploding of the missile, a rotor adjacentthe rear end of the casing carrying detonator means and adapted to berotated from a safety position to a firing position, a movable hammeradapted at the rear end thereof to engage the rotor to hold the rotor inlocked safety position, and actuating means for moving the hammer out ofengagement with the rotor to permit rotation of the rotor from thelocked safety position to an armed position whereby the detonator meansis placed in line with the hammer when the fuse is actuated for firing,the said fuse having a safety arrangement for locking the hammer in therest position and for allowing the hammer to move from the rest to thearmed position only after a predetermined time delay after firing of themissile, characterized by a housing in said casing having a chambertherein, a piston on the forward end of said hammer adapted to beslidably received in the chamber of said housing, a plurality of ballsconfined in said housing by the piston on said hammer with the ballsnormally holding the hammer in rest position, an exit passage in thewall of the housing from said chamber, and an inertia operated memberslidably mounted on said housing and closing said exit passage when thefuse is in rest position and slidable to a position to open said exitpassage when the missile is fired to permit flow of the balls throughthe exit passage over a predetermined delayed period of time so that thehammer is free to move forward out of engagement with the rotor and therotor is then free to rotate under centrifugal force to position thedetonator in position to be detonated by the hammer when the fusestrikes an object.
 1. A fuse for a missile, comprising a casing having abooster at the rear end of the casing for exploding of the missile, arotor adjacent the rear end of the casing carrying detonator means andadapted to be rotated from a safety position to a firing position, amovable hammer adapted at the rear end thereof to engage the rotor tohold the rotor in locked safety position, and actuating means for movingthe hammer out of engagement with the rotor to permit rotation of therotor from the locked safety position to an armed position whereby thedetonator means is placed in line with the hammer when the fuse isactuated for firing, the said fuse having a safety arrangement forlocking the hammer in the rest position and for allowing the hammer tomove from the rest to the armed position only after a predetermined timedelay after firing of the missile, characterized by a housing in saidcasing having a chamber therein, a piston on the forward end of saidhammer adapted to be slidably received in the chamber of said housing, aplurality of balls confined in said housing by the piston on said hammerwith the balls normally holding the hammer in rest position, an exitpassage in the wall of the housing from said chamber, and an inertiaoperated member slidably mounted on said housing and closing said exitpassage when the fuse is in rest position and slidable to a position toopen said exit passage when the missile is fired to permit flow of theballs through the exit passage over a predetermined delayed period oftime so that the hammer is free to move forward out of engagement withthe rotor and the rotor is then free to rotate under centrifugal forceto position the detonator in position to be detonated by the hammer whenthe fuse strikes an object.
 2. A fuse according to claim 1, wherein theinertia operated member is a ring assembled around said cylinder, pinmeans securing the inertia operated member in the position to close theaperture and being sheared upon firing of the missile by the inertiaoperated member as the latter by inertia slides on said cylinder andopens said aperture for release of the balls from the cylinder.
 3. Afuse according to claim 1, wherein the rotor has a central elongatedhole to receive the inner end of the hammer to hold the rotor innon-firing position.
 4. A fuse according to claim 1 wherein said housingis an axially extending cylinder with one portion of the cylinder havinga greater diameter than a second portion anD an annular shouldertherebetween, said shoulder adapted to be crushed on impact of the fuse.